Radio systems are systems that transmit and receive signals in the form of electromagnetic waves in the RF range of approximately 3 kiloHertz (kHz) to 300 gigaHertz (GHz). Radio systems are commonly used for wireless communications, with cellular/wireless mobile technology being a prominent example.
A phase shift module is an RF network module which provides a controllable phase shift of an RF signal. Phase shifters may be used in phased arrays, where, in antenna theory, a phased array usually refers to an electronically scanned array of antenna elements which creates a beam of radio waves that can be electronically steered to point in different directions without moving the antennas. In an array antenna, the RF current from the transmitter is fed to the individual antennas with the correct phase relationship so that the radio waves from the separate antennas add together to increase the radiation in a desired direction, while cancelling to suppress radiation in undesired directions. In a phased array, the power from the transmitter is fed to the antennas through phase shifters, controlled by a computer system, which can alter the phase electronically, thus steering the beam of radio waves to a different direction.